Replaceable wet-set tactile warning surface unit and method of installation and replacement

ABSTRACT

A replaceable, wet-set tactile warning surface unit having a body defining an upper surface and a lower surface, the body defining a series of raised projections on its upper surface, and defining a plurality of spaced through-holes from the top to the bottom surface, in which the raised projections are spaced from one another and the through-holes are located between projections. An anchor member such as a threaded insert is coupled to the bottom surface of the unit member directly below each of the through-holes by fasteners such as bolts that pass through the through-holes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/251,620, which is a continuation of U.S. patent application Ser. No.12/849,564, which issued as U.S. Pat. No. 8,028,491, which is acontinuation of U.S. patent application Ser. No. 12/115,595, whichissued as U.S. Pat. No. 7,779,581, which in turn claims priority ofProvisional Patent Application Ser. No. 60/916,887, filed on May 9,2007,and Provisional Patent Application Ser. No. 61/014,361, filed onDec. 17, 2007, the entire disclosures of which are incorporated hereinby reference.

FIELD OF THE INVENTION

The present invention relates to a wet set replaceable tactile warningsurface unit that can be embedded in fresh concrete, but can be quicklyand easily removed and replaced without disturbing the underlyingsubstrate.

BACKGROUND OF THE INVENTION

Tactile Warning Surface (TWS) products are required in certain locationsunder the Americans with Disabilities Act Accessibility Guidelines(ADAAG). The ADAAG defines certain types of applications, including curbramps/pedestrian crossings, commercial applications (e.g., big boxretailers, hotels and restaurants) and transit facilities (e.g.,commuter rail, rapid transit and Bus Rapid Transit (BRT)). The visuallyimpaired may elect to utilize TWS products to detect hazardous drop-offs(platform edge/loading dock) and hazardous vehicular areas (curb rampson street corners and intersections, uncurbed transition betweenpedestrian and vehicular areas such as at the front of big box retailestablishments).

Visually impaired and fully sighted persons may rely on a combination ofvisual cues (color contrast), tactile cues (sweeping cane, sole of shoe,through wheelchair wheels, walker wheels), and audio cues (soundattenuation, which can be achieved by use of dissimilar materials suchas composite TWS and concrete substrate) when electing to use TWSproducts as a means of edge and hazardous vehicular area detection.

TWS products define a series of spaced raised truncated domes. See,e.g., U.S. Pat. No. 7,001,103 for a discussion of TWS products. Theseproducts are typically installed in curb ramps, pedestrian ways andcommercial areas by setting into the fresh concrete a plastic, compositeor metal TWS product that defines on its upper surface the series ofspaced raised truncated domes required by the ADAAG. Although suchCast-In-Place (CIP) TWS products are easy to install into wet concrete(typically taking only a few minutes), replacement is difficult and timeconsuming, and replacement costs are high, because the underlyingsubstrate must be at least partially destroyed in order to remove aninstalled product, and then reconstructed for the replacement product.

Some of these CIP TWS Units define a relatively thin upper surface layersupported underneath by spaced honeycomb-like lower walls that are setin fresh concrete. Air can be trapped between the lower walls, whichcreates areas underneath the CIP TWS Unit that are not supported by theunderlying substrate. Because they are thin to begin with, and in spotsnot supported, these CIP TWS Units can fatigue and crack under moderateor heavy loading, such as can be caused by pallet jacks, fork lifts andvehicles, for example. Also, due to the plurality of intersecting lowerwalls that are embedded in concrete, in some cases these CIP TWS Unitscannot be replaced without tearing up and then rebuilding the concretestructure in which they were set; this is a time consuming and expensiveproposition.

Another issue with ADAAG-compliant TWS products is that the projectingdomes can be broken or sheared off by snowplows or the like, requiringreplacement. Some fiberglass-reinforced epoxy resin TWS products have abody that is reinforced by a woven fiberglass mat. However, the domesare constructed of pure resin without any fiberglass reinforcement forimpact resistance. These TWS products thus have projecting domes thatare inherently weaker than the body. The domes thus can be more easilycracked, broken or sheared off.

Some CIP TWS Units are set into fresh concrete with fasteners that passthrough holes located in the domes. There are also CIP TWS Units inwhich the head of the fastener is shaped like a dome, in which case thefastener is located in place of one of the domes. In both such cases, ifa dome is sheared or broken off, there is danger that the head of thefastener can be sheared or broken off, or at a minimum the fastener canbe loosened. If this happens, the TWS product can come loose and presenta tripping hazard.

The prior state of the art for new construction includes composite shellCIP TWS Units. Composite shell CIP TWS Units are quickly andeconomically installed; however, if the installer is not diligent CIPTWS Units are susceptible to air entrapment underneath the CIP TWS Unitand are thus susceptible to fatigue and cracking failure due torepetitive and/or heavy loading. Fatigue and cracking failure underrepetitive heavy loading may also occur along the relatively thinperimeter flange structure. Once installed, CIP TWS Units arepermanently embedded into the concrete substrate and it is thusdifficult, invasive, time consuming, and costly to remove and replaceCIP TWS Units when maintenance is required.

Another solution is a surface applied (SA) TWS panel that is applied toa finished substrate. A SA TWS panel is typically mechanically fastened(e.g., with a nylon sleeve anchor with a stainless steel pin) andadhered (e.g., using single component urethane adhesive) to theunderlying substrate, and then caulked around the perimeter tocompensate for substrate irregularities, minimize water intrusion, andprovide a superior architectural finish. Installation takes 10-15minutes for a 2′×4′ SA TWS panel. Replacement of a SA TWS panel iseasier than with a CIP TWS Unit, and is typically accomplished byremoving the fasteners, heating the SA TWS panel to break the adhesivebond with the underlying substrate, prying the TWS panel off thesubstrate, removing existing adhesive, and installing a new SA TWSpanel. The substrate basically remains intact. Perhaps 1 to 1½ hourslabor is involved. Replacement cost is thus moderate. However, these SATWS panels can more easily loosen or dislodge as compared to CIP TWSunits. For example, a protruding edge or corner of the SA TWS panel canbe caught by a snow plow and lifted. This can present a safety hazard.SA TWS panels are thus not as acceptable as CIP TWS Units. SA TWS panelsare an ideal solution for retrofit applications; CIP or replaceable(REP) TWS Units are an ideal, quick, and economical solution for newconstruction. The elevation of the body of a SA TWS panel is at least ⅛″above the surface of the underlying substrate; consequently, the body ofthe SA TWS panel is potentially vulnerable to damage from snow removaloperations. The body of CIP or REP TWS Units are flush mounted relativeto the adjacent substrate; consequently, the body of the TWS Unit isshielded or protected from damage due to snow removal operations. Flushmounted TWS Product installations offer superior performance whencompared to surface mounted TWS Product installations. As the fastenersin SA TWS Panels are located within the truncated dome, they arevulnerable to damage from snow removal or similar shearing type actionthat the domes may be subjected to under everyday use.

There is thus the need for a wet-set replaceable TWS Unit that is ruggedso less likely to be damaged or loosened from the underlying substrate,uses fasteners that are less likely to be damaged by heavy equipment,and can be quickly, easily and economically replaced withoutreconstruction of the underlying substrate (such as a curb ramp ortransit platform), or dealing with adhesive application and removal.

SUMMARY OF THE INVENTION

This invention features a heavy-duty, wet-set, replaceable tactilewarning surface (TWS) unit that installs easily. One embodiment of theinventive wet set TWS unit comprises a body defining an upper surfaceand a lower surface, the body defining a series of raised projections onits upper surface, and defining a plurality of spaced through-holes fromthe top to the bottom surface, in which the raised projections arespaced from one another and the through-holes are located in the fieldbetween projections. The wet set TWS Unit has an equal plurality ofanchor members coupled to its bottom surface directly below thethrough-holes by an equal plurality of fasteners (such as bolts) thatpass through the through-holes.

The inventive wet set TWS Unit is preferably unitary, solid andessentially homogeneous. In one embodiment, the body is made from achopped fiber (e.g., fiberglass) reinforced resin composite material,and the unitary projections are also made from the same compositematerial. Alternatively, the body and the projections may be made from ametal material, such as stainless steel. The body may define a perimeterflange that is thicker than the rest of the body. The inventive unit mayin that case further comprise a plurality of spaced slots passingthrough the perimeter flange that allow air to escape from underneaththe unit when it is installed in fresh concrete; the slots maycommunicate with the bottom of the flange and the area underneath thebody inside of the flange. The perimeter flange may define an innersurface (and potentially also an outer surface) that is tapered suchthat the bottom of the flange is narrower than the top of the flangewhere it meets the rest of the body, to facilitate removal of theinventive unit from set concrete. The perimeter flange may be about oneinch wide. In one specific embodiment, the perimeter flange has athickness of about ⅝.sup.th inches, and the rest of the body, with theexception of the locations of the projections, has a thickness of about⅜.sup.th inches.

The raised projections may define truncated dome shapes. The size, shapeand pattern of the truncated domes preferably meets the presentrequirements for the ADAAG. At least some of the upper surface betweenprojections may define a roughened surface. The roughened surface may beaccomplished with a large number of small projecting asperities that arepreferably on essentially the entire surface, including the tops of thedomes.

The anchor members preferably comprise metal concrete inserts. Thefasteners (bolts) are preferably metal hex-cap bolts. The lower surfaceof the body surrounding each of the through-holes may define adownwardly-protruding lower projection. The downwardly-protruding lowerprojections may define a tapered, generally truncated conical shape suchthat the bottom of the projection is narrower than the location at whichthe projection meets the rest of the body. The conical shape of thelower projections may define a taper angle of about 120 degrees.

The body proximate each through-hole may be offset downward to define arecess in the upper surface. The fasteners may define an enlarged headthat is located in a recess, such that the head does not project abovethe upper surface of the body that surrounds the recess. There may be anequal plurality of watertight structural caps that are fitted into therecesses to cover the heads of the bolts. The structural caps may definea generally circular perimeter with a flat area. The recesses may definea shoulder, in which case the caps sit on the shoulders. The cap ispreferably both structural and provides an essentially watertight sealto the body.

Also featured is a method of installing the inventive unit, comprisingplacing it into fresh concrete and applying force to the top of the wetset REP TWS unit to embed it in the concrete such that its edges areapproximately flush with the top surface of the concrete. There are few,if any, air pockets underneath the installed inventive unit, whichprovides it overall with superior support from the underlying substrate.This, along with the thickness and uniformity of the body, and thethickened perimeter flange, accomplish a wet set REP TWS Unit that ismuch less likely to crack or break than other composite TWS products.

The inventive unit may be replaced if necessary by removing the caps andbolts, prying it off of the underlying substrate, and leaving theinserts (anchor members) embedded in the underlying concrete substrate.An essentially identical replacement TWS Unit is then placed on thesubstrate such that its through-holes are aligned with the embeddedinserts, and fixing the replacement unit to the substrate by passingbolts through the through-holes and into the internally threadedinserts.

In a more specific embodiment, the invention features a wet-set REP TWSUnit comprising an essentially solid and homogeneous generally flat bodymade of a fiberglass-reinforced resin composite material, and definingan upper surface and a lower surface, the body further defining a seriesof integral spaced raised projections on its upper surface, in which theraised projections define truncated dome shapes, the size, shape andpattern of the truncated domes meeting the present requirements for theADAAG. The body further defines a perimeter flange that is thicker thanthe rest of the body, the perimeter flange defining an inner surfacethat is tapered such that the bottom of the flange is narrower than thetop of the flange where it meets the rest of the body, to facilitateremoval of the inventive unit from a fully cured concrete substrate. Thebody further defines a plurality of spaced through-holes from the top tothe bottom surface that are located in the field between projections, inwhich the body proximate each through-hole is offset downward to definea recess in the upper surface, and in which the lower surface of thebody surrounding each of the through-holes defines adownwardly-protruding lower projection that defines a tapered, generallytruncated conical shape such that the bottom of the projection isnarrower than the location at which the projection meets the rest of thebody. There are a plurality of flared threaded inserts, one coupled tothe bottom surface of the body directly below each of the lowerprojections by an equal plurality of fasteners (bolts) that pass throughthe through-holes, in which the bolts define an enlarged head that islocated in a recess, such that the head essentially does not projectabove the upper surface of the body that surrounds the recess.

Another more specific embodiment features a wet-set REP TWS Unitcomprising an integral metal body defining an upper surface and a lowersurface, the body further defining a series of integral spaced raisedprojections on its upper surface, in which the raised projections definetruncated dome shapes, the size, shape and pattern of the truncateddomes meeting the present requirements for the ADAAG. The body furtherdefines a plurality of spaced through-holes from the top to the bottomsurface that are located in the field between projections, in which thebody proximate each through-hole is offset downward to define adepression in the upper surface. There are a plurality of threadedinserts (anchor members), one coupled to the bottom surface of the bodydirectly below each of the through-holes by an equal plurality offasteners (bolts) that pass through the through-holes, in which thebolts define an enlarged head that is located in a depression, such thatthe head essentially does not project above the upper surface of thebody proximate the recess.

The inventive REP TWS Unit is of a heavy-duty construction thattypically will not crack or fatigue under heavy vehicular loading. Theinventive unit is quick and easy to install, with essentially no airentrapment, which causes failure in most CIP TWS products. The inventiveunit is quickly and economically replaced without disturbance to theunderlying substrate. This makes the inventive unit particularlyadvantageous to big box retailers that need to periodically replace TWSProduct at store entrances with little or no disruption to retailoperations or inconvenience to customers of the retail establishment.(The inventive REP TWS Unit can be replaced when the store is shut down,with the area ready for customer use for the next day's retailoperation. Little skill is required to install the inventive REP TWSUnit.)

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features and advantages of the present inventionwill become fully appreciated as the invention becomes better understoodwhen considered in conjunction with the accompanying drawings showingnon-limiting embodiments of the invention, wherein like numbers are usedfor like parts, and lower case letters are used where a part is the sameor performs the same function as a part given the same number without alower case letter, and in which:

FIGS. 1A, 1B, 1C and 1D are top, side, bottom and end views,respectively, of a first embodiment of the wet-set REP TWS Unit of theinvention;

FIG. 1E is a cross-sectional view taken along line E-E of FIG. 1A;

FIG. 1F is a partial, enlarged cross-sectional view of portion 30 ofFIG. 1E, showing the concrete in which the inventive unit is set;

FIG. 2A is an enlarged partial top view showing one structuralwatertight cap assembled onto the body of the first embodiment of theinvention;

FIG. 2B is a partial, enlarged, bottom perspective view of the firstembodiment of the inventive unit;

FIG. 3A is a view similar to that of FIG. 1F, but showing a fasteneradded to the inventive unit;

FIG. 3B is a top view of FIG. 3A;

FIG. 4A is a partial top view of a second embodiment of the wet set REPTWS Unit of the invention;

FIG. 4B is an enlarged view of a surface dimple pattern of the secondembodiment of the inventive unit;

FIG. 5A is a cross-sectional view taken along line A-A of FIG. 4A;

FIG. 5B is a cross-sectional view taken along line B-B of FIG. 4A;

FIG. 5C is a greatly enlarged view of area “C” from FIG. 5A;

FIG. 5D is a greatly enlarged view of area “D” from FIG. 5A;

FIG. 6A is a perspective view of the second embodiment of the inventiveunit; and

FIG. 6B is a bottom view of the second embodiment of the inventive unit.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

A first preferred embodiment of the invention is accomplished in afiberglass reinforced resin composite wet set REP TWS Unit 10, shown inFIGS. 1-3. Unit 10 may be a unitary, essentially homogeneousfiberglass-reinforced composite body 40 that defines a plurality ofprotruding, truncated domes 12 and/or other shapes such as oblong barsor other desirable projection shapes. In one embodiment, the size, shapeand spacing of the projections meets the present requirements for theADAAG. Body 40 has upper surface 22 with dimples 14, and lower surface24. Holes 26 pass through the thickness of body 40. These holes areaccomplished by molding into the body a recess 42 in upper surface 22,and an aligned, downwardly-protruding lower projection 41 in lowersurface 24. Projection 41 preferably has a tapered, generally truncatedconical shape defining tapered sides 43. Projections 41 may define ataper angle of about 120 degrees, although such is not a limitation ofthe invention. Lower surface 24 may have small projecting bosses 13 thatadd thickness and thus strength.

In one non-limiting example of the composite wet-set REP TWS Unit of theinvention, some of the key dimensions are as follows: domes 12 may beabout 0.9″ wide at the base and 0.45″ at the top, with a height of 0.2″,and center-to-center spacing of about 2.35″ (the spacing may range from1.6″ to 2.4″; the wider spacing provides more room for unobstructedpassing of wheeled devices such as walkers and shopping carts), with thedomes in a square grid array (also termed “in-line” or orthogonalpattern). Dimples 14 (located on the surface of the unit and the topsurface of the domes, but not shown in all drawings, for the sake ofclarity only) are 90 degree cones about 0.045″ high, and closely spacedtogether. These add to the slip resistance (the coefficient of friction)of the surface, which is about 1.18 dry and 1.05 wet. For comparison,the ADAAG requirements for a non-slip surface are 0.6 wet or dry on aflat surface and 0.8 on a sloped surface. Body 40 is 0.312″ thick, andbosses 13 are 0.062″ high. Lower projections 41 sidewalls 43 are at anangle of about 60 degrees. Watertight structural cap 52 has a diameterof 1.125″.

Inventive unit 10 is preferably essentially solid and unitary andpossesses a slip resistant matte finish, which makes it appear lessslippery, makes it actually less slippery, and also makes it lessreflective, which cuts down on glare when sunlight is at low angles. Thematte finish is perceived to be more slip resistant than a shiny finish,even in a dry state. This provides more comfort for pedestrians. Unit 10is preferably made of a homogeneous chopped fiberglass and resin mixturewith added colorant. The result is that all portions of the unit,including the enlarged flange, the projecting domes and the surfacedimples comprise fiberglass-reinforced composite material. The domesthus do not present weak areas that can more easily crack, shear orbreak as compared to the body of the inventive unit. Also, as the topwears due to foot and vehicular traffic, neither the color nor thecoefficient of friction of unit 10 changes. These advantagesdramatically increase the useful life of unit 10.

In one embodiment, unit 10 is made as follows. The material is athermoset polyester resin based, mineral filled, fiberglass reinforcedcompound. There are additives to control dimensional stability,weathering and appearance. Ultraviolet stability is accomplished using acombination of UV absorbers and hindered amine light stabilizers.Excellent flame spread and smoke density rating per the UL E-84flammability test is produced by a combination of 30 micron and 3.5micron particles of alumina trihydrate filler that together compriseabout 50% of the formulation. There is over 20% fiberglass reinforcementin the compound for strength requirements. The fiberglass used is OwensCorning Fiberglass-957. This glass has good weather resistance for thisapplication. A 65%/35% chop length combination of 1″ and ½″ lengths ofthe fiberglass allow it to flow throughout the substrate and into thetruncated domes for added strength in those areas.

Inventive unit 10 may be manufactured as follows. First, all thecomponents except the fiberglass reinforcement and a chemical thickeningagent (magnesium oxide) are mixed to yield a paste that has theconsistency of thick paint. This is accomplished using a high shearmixing system. Then, the paste is mixed with the thickening agentthrough a series of static mixers, and metered onto a compoundingmachine. At this point the blended paste and thickener are deposited asa thin layer onto the carrier film that acts as the packaging for thefinished blank. The film is a co-extruded film of polyethylene and nylonthat acts as a styrene barrier. The deposition happens at two placesthrough the use of upper and lower doctor boxes. Between these two boxesis where the fiberglass roving goes through a chopper and is depositedon the paste-coated carrier film. The amount of fiberglass per squarefoot and the thickness of the paste determine the final fiberglasspercent, and weight per square foot of the finished blank. These threecomponents come together and go through a compaction system comprised oftwo steel mesh chain belts. Pressure is applied and this action squeezesthe paste and fiberglass together. The fiberglass strands are designedto absorb the paste. The sheet molding compound is sandwiched betweenthe two layers of carrier film and is festooned into a box. Within about24 to 48 hours the chemical thickener acts on the material, changing itto the consistency of leather. The material is then molded to its finalshape.

Inventive unit 10 is adapted to be wet-set into fresh concrete, but canbe easily removed and replaced after the concrete has fully cured. Thisfeature is accomplished by including a plurality of anchors (e.g.,internally threaded inserts) 20 (preferably at least four per unit) thatare mechanically coupled to body 40 by an appropriate means, typicallywith hex-head bolts or similar heavy-duty fasteners 50 with optionalwashers 51, as shown in detail in FIGS. 2A and 2B. The depression orrecess 42 where the bolt head 49 lies is sufficiently deep such that thehead does not project above the upper surface of the body. In this way,snowplows or other heavy equipment moving over the unit cannot catch andbend or shear off the bolt. The bolts are typically located about 5″inside of the perimeter of the unit. This arrangement helps to maintaina sturdy connection of the unit to the underlying supporting substrate,and also reduces the need to add bolt locations when the REP TWS Unit iscut to accommodate most radial applications. Removable structural,watertight cap 52 covers recess 42 and bolt 50 to provide a more uniformappearance and upper surface texture with dimples 14. Cap 52 alsoinhibits the collection of dirt and other debris around the head of thescrew, to facilitate bolt removal. Cap 52 preferably provides awatertight seal to the body of the unit as well, to inhibit waterinfiltration which can lead to corrosion of the bolts thus weakening ofthe coupling of the inventive unit to the underlying substrate. Threadedinserts 20 are typically flared, heavy-duty zinc members, such as 1.5inch long precast concrete inserts. Inserts 20 have a generally tubularmain body with internal threading to accept a threaded fastener, andflared ribs that end at an enlarged lower circular or hexagonal basehaving a diameter of about 1.25 inches. The flared shape and enlargedbase help to firmly embed the anchors (inserts) in the concretesubstrate as it sets. Stainless steel hex-head bolts are typically usedas removable fasteners 50.

The inventive unit is wet-set into fresh concrete as follows: theappropriate number of anchors 20 (one for each opening 26 through whicha fastener 50 passes) are secured to the underside 24 of body 40 with anequal number of bolts 50 and washers 51. Each of the cavities 42 of body40 that accommodates a bolt head are then covered with a cap cover 52that is preferably seated on a shoulder 55 as shown in FIGS. 2A, 2B and2C. It is preferable to remove about ¼″ of concrete to minimize concretedisplacement when pressing the inventive unit in place, and minimizeregarding the adjacent concrete substrate. It is also preferable toinstall the inventive unit when the slump value of the concrete is inthe 4″-7″ range. The assembled inventive unit is then placed down ontothe top of the fresh concrete, often times in a curb ramp, pedestriancrossing or hazardous vehicular way being constructed. The unit is thenset into concrete 59 by pressing down on the it and tamping with arubber mallet or vibrating the unit until it is set such that its top 22is approximately flush with the top of the surface of concrete 59, asshown in FIG. 2A. To ensure that adjacent units are level relative toone another, a small piece of plywood with suitable weight distributedon it may be placed on two or more units, spanning the joint linebetween the units, and left in place until the concrete has set. A ¼″edge treatment may be created around the perimeter to facilitate futurereplacement. Adjacent units should be spaced a nominal ⅛″ apart, toallow for expansion. This can be accomplished by using ⅛″ tile spacerblocks. The perimeter and the joint between adjacent units is caulked(preferably with a urethane sealant) once the concrete has set, toinhibit the collection of water underneath the edges of the inventiveunit.

Since this embodiment is both solid and homogeneous, it can be easilycut and ground to be fitted to a non-rectangular location, or one thatis smaller than the inventive unit itself. If such trimming causes anunacceptable reduction in the number of fastener locations, new fastenerlocations can be added between domes by drilling and countersinkingholes 65 through the body as necessary using a ⅞″ countersink bit.Hex-drive flat-head ½″ bolts 50 a with heads that fit into thecountersunk flared recess are used, as the heads will lie essentiallyflush with or below the upper surface of the inventive unit.

Slots 16 spaced around the perimeter of body 40 (with at least one slot16 along each of the four sides) pass through the thickness of flange 60and extend essentially up to the lower surface of the main portion ofbody 40, to allow essentially all of the air to escape from underneathbody 40 (in the recessed area 31 underneath body 40 inside of flange 60)to the outside as the inventive unit is pushed down into the freshconcrete. This helps to ensure that there are essentially no aircavities beneath body 40 after installation; such air cavities presentareas that are not supported by the concrete that can lead to crackingand failure when the unit is exposed to heavy loads such as pallet jacksand other vehicles passing over the installed unit. The additional 0.25″thickness and 1″ width of perimeter flange 60 adds strength to theperimeter. The perimeter, specifically the upper corners 17 thereof,receive the brunt of impact forces as vehicles move over the unit, andtend to be the locations at which prior, thinner units without a thickerflange, crack and break. The increased thickness of flange 60 helps toprevent such impact-induced failures.

If the inventive unit needs to be removed after the concrete has set,cap covers 52 are pried off; cap covers 52 have one flat side 54 thatcreates a small space 53 between the cap and the walls of hole 26 thatallows the insertion of a screwdriver to pry off the cap. An appropriatetool can then be used to remove the bolts. Due to the draft or angle ofthe downwardly projecting portions 41, and the angle of inner wall 62and outer wall 63 of perimeter flange 60 (resulting in lower flangeportion 61 that is more narrow than where the flange meets the mainbody), the unit can be easily pried off the concrete surface with a prybar or the like. Inserts 20 remain embedded in the concrete. Areplacement unit can then be placed down into the location of theremoved unit with the holes aligned with the embedded inserts, and thenbolted to those inserts.

A second preferred embodiment of the invention may be accomplished in ametal wet set REP TWS Unit 10 a, shown in FIGS. 4-6. Inventive unit 10 amay be a unitary metal (preferably 16 GA type 304L stainless steel) body40 a that defines a series of protruding, truncated domes 12 a that arecompliant with the ADAAG. Dimples 14 a may be interspersed between domes12 a in the field on the surface of body 40 a. Top surface 22 a of body40 a may be coated with a high-grade matte finish exterior gradenon-slip powder coating system. The slip resistance (the coefficient offriction) of the surface is about 0.91 dry and 0.80 wet, both of whichmeet the ADAAG requirements.

Inventive unit 10 a is preferably fabricated from 16-gauge type 304stainless steel. A variety of other material types, materials gauges,and finishing options are available. Alternate materials include, carbonsteel, aluminum, and galvanized steel, along with various other gradesof stainless steel including (but not limited to) 201, 301, 430.Material options are available to allow for a variety of application,durability, or cost considerations. The stainless steel wet set REP TWSUnits offer the highest combined level of strength and corrosionresistance. Aluminum offers a high level of corrosion resistance howeverdoes not provide the same strength as stainless steel. Galvanizedmaterial would offer good corrosion resistance and above averagestrength while carbon steel would offer above average strength but alower level of corrosion resistance compared to the other materialoptions.

The material thickness for inventive unit 10 a is preferably 16-gauge,however the thickness can be up to 11-gauge with appropriate toolingmodifications. Inventive unit 10 a can be fabricated on a press machineusing custom designed and fabricated punch tooling. The panels areadjusted for flatness as necessary to relieve stresses in the materialcreated by the punching process. Appropriate bends are added to thepanel for required final application. Two-layer powder paint is appliedto protect the panel from wear and weather. Stage I is the applicationof a Sherwin Williams POWDURA® Epoxy Powder Coating primer while StageII is the application of a Sherwin Williams POWDURA® Polyester PowderCoating topcoat of specified color. Alternate painting options arepossible based on specific application. Laboratory testing has indicatedthat the primer coat provides little or no additional corrosionresistance protection compared to only one layer of topcoat on thestainless steel panels.

Inventive unit 10 a is adapted to be wet-set into fresh concrete, butcan be removed and replaced after the concrete has fully cured. Thisfeature is accomplished by including a plurality of anchors (inserts) 20a that are mechanically coupled to body 40 a by an appropriate means,typically with hex-head bolts 50 b in countersunk holes 42 a. Anchors 20a are typically flared, heavy-duty zinc or stainless steel members, suchas the concrete inserts described above. Stainless steel hex-head boltsare preferably used as the removable fasteners.

In one non-limiting example of the metal wet-set REP TWS Unit of theinvention, some of the key dimensions are as follows: domes 12 a may beabout 0.9″ wide at the base and 0.45″ at the top, with a height of 0.2″.Dimples 14 (located on both the surface of the inventive unit and thetop surface of the domes) are 90 degree truncated cones about 0.040″high, 0.12″ wide at the base, and 0.040″ wide at the top, and closelyspaced together. These add to the slip resistance (the coefficient offriction) of the surface. Body 40 a is 0.060″ thick. The walls of holes42 a are at an angle of about 43.5 degrees from the horizontal.

Inventive unit 10 a is wet-set into fresh concrete as follows: thedesired number of inserts (one for each opening 26 a) are secured to theunderside of body 40 a with an equal number of bolts 50 b. The assembledunit is then placed down onto the top of fresh concrete, often times ina curb ramp, pedestrian crossing or hazardous vehicular way beingconstructed. Inventive unit 10 a is then set into the concrete bypressing down on it until it is set such that its top 28 a is flush withthe top of the surface of the concrete. Weep holes 29 pass throughflange or edge 60 a very close to where edge 60 a meets body 40 a toallow air to escape from beneath unit 10 a as it is installed, in asimilar fashion as the slots 16 in the first embodiment described above.

If body 40 a needs to be removed after the concrete has set, anappropriate tool is used to remove the bolts. Due to the draft or angleof the downwardly projecting portions 42 a and the edges 60 a of body 40a, body 40 a can be pried off the concrete surface with a pry bar or thelike. A replacement body can then be placed down into the location ofthe removed body, and bolted to the inserts that remain embedded in theconcrete.

With respect to the above description then, it is to be realized thatthe optimum relationships for the elements of the invention, to includevariations in size, materials, shape, form, function and manner ofoperation, assembly and use, are deemed apparent to one skilled in theart, and all equivalent relationships to those illustrated in thedrawings and described in the specification are intended to beencompassed by the present invention.

Therefore, the foregoing is considered as illustrative only of theprinciples of the invention. Further, since numerous modifications andchanges will occur to those skilled in the art, it is not desired tolimit the invention to the exact construction and operation shown anddescribed, and accordingly, all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention.

1. A replaceable, wet-set tactile warning surface unit, comprising: aunitary resinous composite body defining an upper surface and a lowersurface, the body comprising a series of raised projections on its uppersurface, a plurality of projecting asperities disposed on the uppersurface and on the top of the raised projections, and a plurality ofspaced through-holes passing through the body; anchor members coupled tothe unit below the through-holes by fasteners that pass through thethrough-holes; a flange extending from the lower surface at or near eachside of the unit; and an unenclosed vent along each of the sides andlocated underneath the body that allows air to escape from underneaththe unit when it is installed in fresh concrete and that prevents thebody from being permanently embedded in set concrete.
 2. Thereplaceable, wet-set tactile warning surface unit of claim 1, whereinthe number of spaced through holes equals the number of anchor members.